[PATCH 7/9] media: camss: video: stop the subdevices already started when a start fails

[Qianhui Xu]

When one subdevice fails to start, the ones already started further up the
pipeline were left streaming, and the next start would try to start them
again.  Factor the teardown loop out of video_stop_streaming() into
video_stop_subdevices() and run it from the error path, stopping at the
subdevice that failed.

While at it, keep stopping the remaining subdevices when one of them fails
to stop instead of returning early: the pipeline is being torn down, so a
failure there must not leave the rest running.

Signed-off-by: Qianhui Xu <xiaqinghuan@xxxxxxxxxxxxxxxx>
---
 .../media/platform/qcom/camss/camss-video.c   | 60 +++++++++----------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/drivers/media/platform/qcom/camss/camss-video.c b/drivers/media/platform/qcom/camss/camss-video.c
index 027cf024f..ee9ffd043 100644
--- a/drivers/media/platform/qcom/camss/camss-video.c
+++ b/drivers/media/platform/qcom/camss/camss-video.c
@@ -265,11 +265,37 @@ static int video_prepare_streaming(struct vb2_queue *q)
 	return ret;
 }
 
+/* Stop the started subdevices, excluding the one that failed to start. */
+static void video_stop_subdevices(struct camss_video *video,
+				  struct media_entity *stop)
+{
+	struct media_entity *entity = &video->vdev.entity;
+	struct v4l2_subdev *subdev;
+	struct media_pad *pad;
+	int ret;
+
+	while (entity != stop) {
+		pad = &entity->pads[0];
+		if (!(pad->flags & MEDIA_PAD_FL_SINK))
+			break;
+		pad = media_pad_remote_pad_first(pad);
+		if (!pad || !is_media_entity_v4l2_subdev(pad->entity))
+			break;
+		entity = pad->entity;
+		if (entity == stop)
+			break;
+		subdev = media_entity_to_v4l2_subdev(entity);
+		ret = v4l2_subdev_call(subdev, video, s_stream, 0);
+		if (ret && ret != -ENOIOCTLCMD)
+			dev_err(video->camss->dev, "Video pipeline stop failed: %d\n", ret);
+	}
+}
+
 static int video_start_streaming(struct vb2_queue *q, unsigned int count)
 {
 	struct camss_video *video = vb2_get_drv_priv(q);
 	struct video_device *vdev = &video->vdev;
-	struct media_entity *entity;
+	struct media_entity *entity = &vdev->entity;
 	struct media_pad *pad;
 	struct v4l2_subdev *subdev;
 	int ret;
@@ -284,7 +310,6 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
 	if (ret < 0)
 		goto error;
 
-	entity = &vdev->entity;
 	while (1) {
 		pad = &entity->pads[0];
 		if (!(pad->flags & MEDIA_PAD_FL_SINK))
@@ -305,6 +330,7 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
 	return 0;
 
 error:
+	video_stop_subdevices(video, entity);
 	video_device_pipeline_stop(vdev);
 
 flush_buffers:
@@ -316,35 +342,9 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
 static void video_stop_streaming(struct vb2_queue *q)
 {
 	struct camss_video *video = vb2_get_drv_priv(q);
-	struct video_device *vdev = &video->vdev;
-	struct media_entity *entity;
-	struct media_pad *pad;
-	struct v4l2_subdev *subdev;
-	int ret;
-
-	entity = &vdev->entity;
-	while (1) {
-		pad = &entity->pads[0];
-		if (!(pad->flags & MEDIA_PAD_FL_SINK))
-			break;
-
-		pad = media_pad_remote_pad_first(pad);
-		if (!pad || !is_media_entity_v4l2_subdev(pad->entity))
-			break;
-
-		entity = pad->entity;
-		subdev = media_entity_to_v4l2_subdev(entity);
-
-		ret = v4l2_subdev_call(subdev, video, s_stream, 0);
-
-		if (ret) {
-			dev_err(video->camss->dev, "Video pipeline stop failed: %d\n", ret);
-			return;
-		}
-	}
-
-	video_device_pipeline_stop(vdev);
 
+	video_stop_subdevices(video, NULL);
+	video_device_pipeline_stop(&video->vdev);
 	video->ops->flush_buffers(video, VB2_BUF_STATE_ERROR);
 }